Gossamer Bio, Inc. (Nasdaq: GOSS) announced it plans to submit a New Drug Application (NDA) for seralutinib, a treatment for pulmonary arterial hypertension (PAH), in September 2026, following a Pre-NDA Type B meeting with the U.S. Food and Drug Administration (FDA) and receipt of official meeting minutes.

The FDA characterized the degree of statistical significance and the magnitude of the treatment effect observed in the Phase 3 PROSERA trial as review issues rather than filing issues. On that basis, Gossamer intends to support the NDA with data from the PROSERA study, the Phase 2 TORREY study, and supportive analyses. If the NDA is accepted for filing, an FDA approval decision could come in the third quarter of 2027.

Gossamer also announced it has reacquired worldwide development and commercial rights to seralutinib from Chiesi following the termination of their Collaboration and License Agreement. Under the termination terms, Chiesi will make a one-time $5 million payment to Gossamer, with no upfront cash payment required from Gossamer. Chiesi retains a capped royalty on worldwide net sales and is eligible for specified regulatory and commercial milestone payments. The termination dissolves the prior U.S. 50/50 profit share arrangement and returns ex-U.S. rights to Gossamer.

At a special stockholder meeting held July 14, 2026, shareholders approved proposals related to the exchange of approximately $181.1 million, or 90.5%, of the company's 5.00% Convertible Senior Notes due 2027 for approximately $65.2 million of new 7.50% Convertible Senior Secured First Lien Notes due 2030, along with equity securities and warrants. The transaction reduced the company's aggregate principal debt by approximately $115.9 million. Stockholders also authorized the board to effect a reverse stock split, which the company expects to complete in or shortly after the third quarter of 2026.

On a preliminary basis, Gossamer reported cash, cash equivalents, and marketable securities of approximately $57 million as of June 30, 2026.